A light emitting diode (LED) is a semiconductor device that is configured to receive electrical power or stimulation and to output electromagnetic radiation, commonly in the visible range of the spectrum (light). Portions of a LED comprise doped semiconductor materials that operate to combine charge in a way that releases said light energy from the body of the LED material. This effect is sometimes referred to as electroluminescence. The output energy or light is determined by the materials and operating conditions of the LED, including the energy band gap of the LED material and the electrical biasing of the LED.
Light emitting diodes (LEDs) compare favorably to other sources of light and are especially useful in certain applications and markets. For example, LED lighting generally provides advantages with respect to energy efficiency, compact and rugged and long-lasting design and form factor, and other features. LED lighting compares favorably with other sources in the amount of light energy generated in the visible electromagnetic spectrum compared to the infra-red or heat energy wasted by the light source. In addition, LED lights include fewer environmentally damaging components when compared to other light forms, and therefore provide better compliance with restrictions on hazardous substances (RohS) regulations.
That said, conventional LED devices can be relatively costly to manufacture by some metrics when compared to other light sources. One reason for this is the exacting packaging requirements for manufacturing LEDs. LED packaging calls for proper clean conditions, micro-fabrication facilities similar to other semiconductor manufacturing operations, sealing requirements, optical requirements, the use of phosphor in LED applications, as well as packaging that is designed to handle the conduction of heat generated in the devices.
Conventional LED packaging includes silicon (Si) or Ceramic based carrier substrates. The LEDs can be mounted on the carrier, or alternatively the many LEDs can be mounted on a wafer of the carrier and the LEDs are singulated at the end of the packaging process. The wafer based approach is termed wafer level assembly packaging (WLP). However, these conventional techniques require the use of a carrier substrate to support the LED, which can double the cost of making and packaging the LED device. In addition, the carrier substrate greatly increases the thermal resistivity of the device and adversely affects its heat removal characteristics.
Accordingly, there is a need for LED devices that do not suffer from some or all of the above problems.